Treating ore concentrates



Aug. 2, 1960: F. D. DE VANEY 2,947,026

TREATING ORE concsmw'anss Filed March 23, 1956 5 Sheets-Sheet 1 INVENTOR ATTORNEYS Aug. 2, 1960 F. D. DE VANEY 2,947,026

TREATING ORE CONCENTRATES Filed March 23, 1956 5 Sheets-Sheet 2 IN VENTOR A.; ATTORNEYS D. DE VANEY TREATING ORE CONCENTRATES Aug. 2,1960

5 Sheets-Sheet 3 Filed March 23, 1956 INVENTOR i; ATTORNEY-5 Aug. 2, 1960 F. D. DE'VANEY TREATING ORE CONCENT RATES Filed March 23, 1956 i 5 Sheets-Sheet 4 INVENTOR WWW/1 .;v ATTORNEYS Aug. 2, 1 960 F. D. DE VANEY TREATING ORE CONCENTRATES 5 Sheets-Sheet 5 Filed March 23, 1956 INVENTOR 7L; ATTORNEYS 'surface, e.g.,

United States i? atent 2,947,026" 7 v V TREATING ORE CONCENTRATES Fred D. De Vaney, HibbingpMinm, assignor to Erie Mining Company, Hibbing, Minn., a corporation of Minnesota 7 Filed ar. 23, 1956, Ser. No. 573,419. 2 Claims. cl. 1s i) specific description the present invention will be; described with particular. reference to pelletizing rnoist oxidic iron ore concentrates. f

In balling moist particles of mineral solids it heretofore had, been proposed to roll the same on an inclined the inner peripheral surface of a revolving conically shaped vessel-called herein a balling cone but sometimes colloquially referred to as a .flying ,saucerand to prevent build-up of the moist particles of mineral solids. on, such inner peripheral surface by continuously scraping off any adhering particles therefrom. However, the clean metallicinner surface promoted sliding, rather than rollin'g, and hence it became apparent that a rolling surface should be provided which would promote positive rolling of the material being treated.

Accordingly, the conventional method of operating balling cones is to provide a stationary scraper on the sloping sides of the cone at either the 10 or 12 oclock position. It is also rather common to position a stationary scraper at the closed end of the cone .at, say, the 12 oclock position. These scrapers maintain a coating or adherent layer. of the moist, finely divided mineral solids, said coating having a desired thickness, but tend to give the same a slick, smooth surface on which the balls tend to slide rather than roll. A still greater objection to the use of stationary scrapers is that the drum cake becomes, with continuous scraping, very hard causing excessive power consumption and chattering of the scrapers. This chattering causes the drum to roll unevenly and the balls to bounce; this latter, in turn, causes undesirable ball breakage." chattering may become so'severeas to tearthe drum loose from its supporting spider andsupporting bearings. I 7

According to the present invention, theformation of the moist particles into small balls or pellets is effected on a specifically prepared rolling surface-as distinguished from a clean metal surface-by a procedure which is characterized in that moist particles of mineral solids are permitted to adhere to the inner peripheral surface of the balling cone, to the formation thereover of a I compacted bed orlayer thereof, and the thicknessof such compactedlayer is limited to, a predetermined arbitrary value and simultaneously its'upper (outer) surface is prepared by continuously doctoring (i.e.,; scraping) the same at a plurality of relatively very narrow, separate areas therealong and progressively shifting the; zone of ;doctoring longitudinallypf the balling vessel so as to effect eventual doctoring of the entire area of the compacted PatentedAugxZ, Iss0 2 layer adhering to the sloping walls of the balling cone thereby maintaining over said surface a condition of controlled roughness promoting positive rolling of the moist material thereover.

Apparatus for use in carrying out this procedure comprises, in combination with the rotatable balling'cone and its supporting and driving mechanisms-which balling cone is per se old and not herein claimed as such-a doctoring means which is stationary with respect to the rotation of the balling cone and which doctors the exposed surface of the aforesaid compacted layer at a plurality of spaced apart, relatively very narrow paths ex-. tending circumferentially of said surface, said doctoring means including means for progressively shifting said paths laterally whereby to elfect eventual doctoring of the entire area of the exposed surface of said compacted layer.

Preferably, said doctoring means comprises (.1) a rotationally stationary, reciprocatable shaft or cutter bar mounted largely within, and in parallelism to the SIOP-s ing side wall of, the balling cone and carrying aflixed thereto an array of spaced-apart, relatively very'narrow, scraping elements projecting from said cutter bar, after the manner of teeth on a comb, into engagement with the exposed surface of said compacted layer but having their free or outer ends spaced from the sloping side wall of the balling cone by a distance equal to the arbitrarily chosen thickness to which said compacted layer is to be limited, and (2) means-preferably exteriorly of the balling cone-associated with the outer end of said cutter bar and adapted to longitudinally reciprocate the cutter bar in such manner that said scraping elements scrape a plurality of spaced, relatively very narrow, paths in said surface which paths are parallel to each other and, by reason of the reciprocation of the cutter bar, are helical with respect to the compacted layer. Through continued'rotation of the balling cone and continued reciprocation of the cutter bar these narrow helical paths eventually extend across the entire exposed surface of the compacted layer limiting the thickness of thelatter to a predetermined value Whileleaving the surface in'a state of controlled roughness effecting the positive rollingrather than mere slidingof the loose moist particles thereon.

By the expression relatively very narrow paths as used herein 1 mean paths of such slight width that nuclei of appreciable size cannot readily fall thereinto and hence slide on the rather slick bottom surface of the freshly scraped groove, such width lacing of the order of 0.25 inch.

In lieu of the above described doctoring means I can substitute a helical screw positioned with its long axis in parallelism with, and substantially coextensive with, the side wall of the conical balling vessel, together with means for rotating the screw. In this case, the outer edges of the screw are spaced from the inner surface of the side wall a distance equal to the preferred thickness of the adherent layer of moist particulate material to be allowed to remain on the side wall. Preferably, thepitch of the flights of the screw is so selected as to cause the screw-during rotation of the same on its axis-4o cut or doctor a plurality of spaced apart, relatively very narrow paths in the. exposed surface of said layer.

It has been found desirable also to permit an adherent layer of moist fines to'build upon the inner surface of the bottom of the balling. cone, and to continuously.

limit its thickness. Accordingly, I may and preferably do associate with the aforesaid means for doctoring the compacted layer of moist particles adhering to thesloping wall of the balling cone 'a' second doctoring means adapted to continuously limit the thickness of'a layer of the moist particles adhering to the sloping bottom of the balling cone and to provide the aforesaid condition of controlled roughness thereon. Said second doctoring means preferably functions in the upper right hand gradient as seen from the open end of the balling cone. This latter doctoring means may be similar to either of the above discussed two alternative means for doctoring the layer adhering to the side wall of the cone.

The invention will now be described in greater particularity and with reference to the accompanying drawings, in which:

Fig. 1 is a side elevational view with certain nonessential parts removed, of one form of apparatus exemplifying the principles of this invention;

Fig. 2 is a front elevational view of the apparatus shown in Fig. 1', showing relative disposition of doctoring means and of feeding means;

Fig. 3 is a diagrammatic side sectional view, with part of the balling cone cut away, showing details of the means for supporting the balling cone in inclined position and for rotating the same;

Fig. 4 is a fragmentary side sectional view, on line 4-4 of Fig. 2, with bearing means and driving means omitted, showing details of an operable form of reciprocatory cutter bar in combination with a balling cone;

Fig. 5 is a fragmentary side sectional view, on line 5-5 of Fig. 2, with bearing means and driving means and reciprocatory cutter bar omitted, showing details of an operable form of means for do'ctoring a layer of material adhering to the closed end of the balling cone;

Fig. 6 is a fragmentary sectional view similar to Fig. 4, but showing alternative means for supporting the inner end of a reciprocatory cutter bar;

Fig. 7 is a diagrammatic view of a modified form of the apparatus according to the present invention;

Fig. 8 is a fragmentary side sectional view, generally similar to Fig. 5, showing an alte native form of means for operating a rotary doctor for the bottom of the balling cone; and

Fig. 9 is a fragmentary side sectional view, generally similar to Fig. 4, showing an alternative means for doctoring a layer of moist material adhering to the side wall of the balling cone.

In Figs. 1 and 3, the balling cone per se is represented at 10 as being an inclined vessel in the form of a truncated cone, comprising a sloping bottom member 11 and a 4. stationary supporting shaft 17 by means of a first bearing member 27 interposed between the shaft and the annular band end 23 and by means of a second bearing member 28 interposed between the shaft and the sleevelike extension of the spider member.

Power for rotating balling cone 10 is provided by an electric motor 26 feeding, into a variable speed transmission 25 the output of which can be continuously varied over a range of from. about 1170 to about 585 rpm.

The output of the variable speed transmission device is connected by suitable belt drive 30 to the input side of a cone gear (speed reduction) unit generally represented at 34. The motor-transmission unit may, as is indicated at 35 in Fig. 1, be slidably mounted for adconical side wall 12, and having an open mouth 13. In

one actual embodiment the included angle of the conical side wall was about 48, the diameter of the mouth was approximately 14 feet, the horizontal length of side of the cone was approximately 6 feet and the diameter of the closed end of the cone was approximately 9 feet. In this actual embodiment the inner surface of the conical side wall was covered with expanded metal lath, as indicated at 15, spot-welded to the side wall. The purpose of this expanded metal was to provide a medium for the building up and the retention of a compacted layer of moist particles lining the inner surface of the side wall of the device.

A capped sleeve member 19, of larger internal diameter than the diameter of supporting shaft 17, is disposed concentrically about that part of supporting shaft 17 which extends within cone 10 and is secured to said shaft as by pin 19 and hence is stationary.

To the outer side of bottom member 11 there is affixed (as by welding, bolting or the like) the enlarged annular band end 23 of a spider member 23, 24, the elongated sleeve-like extension 24 of which surrounds, is concentric with, and spaced from, that part of stationary supporting shaft 17 which is disposed outside of balling cone 10.

A bull gear 22 is secured to the annular band end 23 of the spider member, with its axis concentric with the axis of shaft 17. The spider member is rotatable about justment of the distance between the same and speed reduction unit 34. To the outer end of output shaft 36 of said speed reduction unit there is keyed a pinion gear 38 which meshes with bull gear 22.

The relative sizes of the gears and the capacity of the speed reduction unit are so selected that the balling cone can be rotated at any desired speed within the range 15-5 r.p.m. Preferably, the rotational speed is adjusted to give a rim travel (at inouth13) of from about 460 feet to about 220 feet per'minute. I

Stationary supporting shaft 17 is mounted on a box girder support member 42' which is secured to a girder framework 45. The spider member is rotatably mounted, intermediate its ends, on box girder support member 42 by means of a third bearing member 46 interposed between the latter and said extension 24, on the one hand, and, on the other hand, between said extension 24 and a bridging support member 43 which ismounted on member 42 and in turn supports the above described drive mechanism.

At its front end (beneath balling cone 10), frame work 45 is provided with two downwardly disposed supporting legs 47, 47' which, adjacent their lower ends, are pivoted as at points 48, 48 to pivot members 49, 49. At its rear end, framework 45 is adjustably secured, as at securing means 52, 52, to fixed support plates 53, 53'. As shown in Fig. l, framework 45 is so disposed that the side wall of the balling cone at its lowermost flight is horizontal, at which disposition the angle of inclination of shaft 17 and of the axis of balling cone 10 is approximately 24 from the horizontal. However, the framework 45 can be given an inclined disposition by suitably pivoting the same, at pivot points 48, 48, by means of a suitable jack 56, so as to g'iv a limited range of inclination thereto and hence to balling cone 10. In this actual installation, the range of variation was 28-20 from horizontal.

The construction above described is, in general, old and for that reason no further detailed description thereof is' necessary.

As shown in Fig. 4, the thickness of the compacted layer of moist particles adhering to 'wall 12 of the balling cone is continuously limited by the doctoring means about to be described. In this embodiment, a cutter bar shaft 60 is disposed mainly within balling cone 10, and adjacent its outer end is supported by a horizontally adjustable, inclined support member 61 and slidable within bushing 62 mounted in support member 61. At its inner end, shaft 60 is slidably supported, parallel to side wall 12 of the balling cone, on yoke member 65 adjustably secured to the outer end of arm 66 radially extending from stationary shaft 17. At its outer end, shaft 60 is provided with a suitable mechanism for reciprocating it in bushing 62 and 'upon yoke member 65, said reciprocating mechanism comprising a speed reducer 70, belt driven by an electric'motor 71, and in turn driving an eccentric device 72 whose linking member 73 is attached to the end of, and functions to reciprocate, shaft 60. As will be well understood, the length of reciprocatory stroke may be adjusted by radially varying the location of the pin of linking member 73; in the actualinstallation being described shaft stroke of slightly in excess of. 4 inches.

but this rate could be modified, as desired, by suitable adjustment of the speed reducer 70;

A plurality of individual scraper members 75, 75 are secured to the shaft 60 so as to'project toward wall 12, their outer ends being spacedfrorn the latter by an interval corresponding to the desired thickness of the compacted layer of moist particles. Scraper members 75, 75 may be and preferably are spaced about 4inches apart along that. portion of shaft 60 which lies within cone 10. Each scraper member presents a chisel-like scraping end having a scraping. width of about 0.25 inch. The interval between the outer ends of scraper members 7 5, 75 and wall 12-and hence the thickness of the layer permitted togadhere to wall 12--may be modified by suitable horizontal adjustment of support member 61 and suitable radial adjustment of yoke member 65 on arm 66. Preferably a layer thickness of about threefourths of an inch to one inch is maintained.

Any appropriate means for introducing loose moist particles into balling cone 10 may be employed, e.g., an endless belt conveyor 78. A screw conveyor type of feeding device, as indicated at 80 (Fig. might be substituted for endless belt conveyor 78.

In this embodiment of the invention, shaft 60 preferably is disposed in the upper left quadrant. That is to say, viewed from the front the ballingcone is revolved in clockwise fashion and shaft 60 is disposed .in the 9l2, oclock quadrant-more particularly at the 10 oclock position, in order to assure that removed material shall fall. onto the material being carried (by rotation) part-way up the rising side of the cone and then rolling back on itself. a

In use of the apparatus above described, balling cone 10 is caused to rotate at about 7.5 r.p.m. (i.e., a rim speed of about 335 feet per minute), and the loose moist pare ticles to be pelletized are fed into the cone at the rate of approximately 1000 pounds per minute. Assuming that a layer of desired thickness previously had been built up over the inner surface of wall 12, the freshly introduced loose moist particles for the most part roll upon the surface of said layer; a small fractional part of the fresh feed tends to adhere to said layer and hence to increase the thickness of the latter. Such freshly adhering material, by rotation of the balling cone, is brought into contact with scraper members '75, 75, and the latter scrape a plurality of parallel, relatively very narrow (0.25 inch) grooves, spaced 4 inches apart, therein down to the desired permanent thickness of said layer. With continuous, relatively slow, reciprocation of the cutter bar, the grooves cu by scraper members 75, 75, are made helical and overlap each other whereby in the course of each complete reciprocation substantially the entire exposed surface of said layer has been doctored to predetermined eX- tent. The resulting doctored surface is desirably rough thereby insuring against slippage between loose particles and layer. Continued rolling of the particles results in the formation of initially tiny nuclei which nuclei gradually grow-by.adherence of particles theretointo small balls or pellets. The growth is gradual, since constant rubbing between adjacent nuclei effects constant attrition as well as adherence of particles to nuclei and compaction of the particles constituting such nuclei. Such gradual growth promotes the formation of dense, mechanically rugged pellets, which characteristics areigenerally critically required from the standpoint of further handling and processing of the pelletized product.

As the pellets accumulate they spill over the rim of mouth 13 and onto a conveyor (not shown) by which they are transported to a point of further processing or use.

In the embodiment so far described, no provision is made for doctoring the surface of a layer of moist par- 60 was given a The rate of reciprocation was made 1 minute (for a complete stroke) ceptable operation bodiment, the bottom member ticles' which may adhere to the slopingsurfa'ce ofbottoni member 11. While it appears to be the fact that doctoring of this latter surface is somewhat less critical-to acof the balling cone-than is doctoring the layer on side wall 12, a definite improvement in performancemay be realized by providing means for limiting the thickness of such bottom layer. This may be effected by the use of a rotatable bottom-doctoring deviceabout to be described-or, in lieu thereof, by the use of a fixed doctor blade secured to that side of arm 66 which is adjacent bottom member 11, the scraping edge of such fixed d'octor blade being spaced from bottom member 11 by an interval equal to the thickness of build-up desired (or tolerable). It is to be understood that such doctor blade functions less. desirably than, and preferably is substituted by, a preferred doctoring means new to be described.

A supporting arm 91 is mounted on stationary sleeve 19 and projects therefrom into the upper right quadrant-preferably in the 2 oclock position. At that end thereof which is remote from sleeve 19 arm 91 is provided member 11, and supports on its inner end a rotary cutter disk 98, which is parallel to and spaced from bottom member 11. A drive pulley 97 is fixed to the outer end of shaft 96, for rotation of the shaft and said disk by any suitable means suchas a belt drive (not shown). On that face of disk 98 which is opposed tobottom member 11 there are fixed a random array over the face of disk 98 in such manner that upon rotation of the disk said scraping elements will scrape circular paths which overlap each other to affect substantially all of the space coextensive with the .area of the disc. Preferably disc 98 is rotated at a speed within the range 5 to 100 r.p.m. Simultaneous rotation of the balling drum brings substantially all of the area of bottom member 11 other end, terminates in a resilient, rubber, bearing socket 87 upon which cutter bar shaft 60 is yieldingly supported. These rubber connections, hich provide firm support for shaft 60 while permitting reciprocatory motion of the latter, tend to reduce vibration of shaft 60.

The apparatus shown inFigs. 1 to 6 can be modified as indicated in Fig. 7. According to this latter em- 11 of the balling cone is imperforate, and shaft 17 (of Figs. 1-6) is substituted by an inclined rotatable supporting shaft 101 which is fixed at its upper end to bottom member 11 and which is maintained-in inclined attitude in suitable bearings 104-, 105, in box girder support member 42 (Fig. 7). A bull gear 22 is secured to the bottom member 11, concentric with the latter, for rotation by means of the pinion gear 38. In this circumstance, the inner end of shaft 60 is not directly supported, said shaft being cantilevered from outside the balling cone at bushed sup port 61, said support and its bushing 62 being made sufliciently elongated to support shaft 60 and to maintain same in desired position. Similarly, the shaft 96 can be supported in desired position simply by bushed support 94, the same, and its bushing 95, being suitably elongated for this purpose.

In this embodiment of the invention, as in the em- ;with a bushing, lgixteriorly of the balling conev bodiment shown in Figs. 1-6, the balling cone preferably is so disposed that its axis is inclined from the horizon at an angle equal to, greater, or less than, one-half the included angle of the conical side wall 12, so as to insure the retention of a suitable bed of the particulate material-and nuclei within the balling cone long enough to permit the growth of nuclei into balls of the optimum size.

In the modification shown in Fig. 8, the hereinbefore described rotating cutter disc is substituted 'by a reciprocatory cutter bar 108 and associated mechanism as follows:

Cutter bar 108' is slidably supported, parallel to and spaced from, the inner surface of bottom member 11, adjacent either end thereof, by means of sliding supporting bearings 110 and 111. Of these latter, bearing 110 is mounted on stationary sleeve 19, while bearing 111 is mounted at the upper end of an inclined supporting shaft 112 whose lower end is mounted on sleeve 19. An electric motor 114 likewise is mounted on sleeve 19, and to its output shaft 115 there is secured a disc 117 having an eccentric groove 118 in that face thereof which is opposite bottom member 11. A pin 120, attached to cutter bar 108, extends into eccentric groove 118 and, upon rotation of said disc, follows said eccentric groove imparting reciprocatory motion to cutter bar 108.

In lieu of the reciprocatory cutter bar, previously described, for doctoring a layer of adhering material on the inner surface of side wall 12, theremay be substituted a rotating helical screw, as illustrated in Fig. 9. In this embodiment, a helical screw 123 is disposed largely within balling cone 10 with its major axis parallel to side wall 12 and disposed substantially in the 10 oclock position, being supported by an outer bearing 124 and an inner bearing 125. Bearing 125 is mounted at one end of a supporting shaft 126 whose other end is fixed to sleeve 19. The outer bearing 124 is mounted on a suitable external support member 128. Bearings 124 and 125 are so disposed that the outer edge of helical screw 123 is spaced from wall 12 by a distance-of the order of 0.751.0 inch-equal to the desired thickness of the layer of material to be permitted to remain adhering to wall 12. At its outer end, helical screw 123 terminates in a shaft 130 to which is affixed a drive pulley 132 adapted to be rotated by a drive belt 133 imparting rotary motion from a source not shown.

Upon rotation of the balling cone 10 and of helical screw 123 the surface of built-up layer of material adhering to wall 12 is progressively, continuously doctored to the predetermined thickness while retaining a condition of controlled roughness over the surface so doctored.

I claim:

\1. Apparatus for forming moist finely'divided loose mineral solid particles such as ore fines into balls, said apparatus comprising an inclined hollow conically shaped vessel provided with a bottom member having a centrally located aperture, said vessel having, during use, at least the greater part of'the inner surface of its conical side wall lined with a compacted layer of the moist particles constituting a rolling surface for the loose moist particles, inclined stationary supporting shaft means projecting through said aperture and into said vessel, means for feeding loose moist particles to the interior of the vessel, means for rotating the vessel about said supporting shaft means, doctoring means for continuously hmiting the thickness of said compacted layer and simulor a few(2or 3)' degrees taneously providing. on the latter a rolling surface of controlled roughness, said doctoring means being stationary with respect to the rotation of said vessel, said doctormember, the free ends of said scraping members being spaced from said side wall and presenting relatively narrow scraping edges, means exteriorly of said vessel for supporting said elongated member in a position parallel to said side wall, a supporting member interiorly ofsaidvessel and bearing on said shaft means for slidably supporting the inner end of said elongated memer, and means exteriorlyof said vessel forimparting reciprocatory motion to said elongated member longitudinally thereof the stroke of such reciprocatory motion being at least equal to the space between adjacent scraping members.

2. Apparatus for forming moist finely divided loose mineral solid particles such as ore fines into balls, said apparatus comprising an inclined hollow conically shaped vessel in the form of a right frustrum of a cone the smaller end of which is closed by a generally plane bottom member having, during use, at least the greater part of the inner surface of its conical-side wall and of its bottom member lined with a compacted layer of moist particles constituting a rolling surface for the loose moist particles, means for feeding loose moist particles to the interior of the vessel, means for rotating the yessel about its inclined axis, first doctoring means for continuously limiting the thickness of the compacted layer on the bottom wall of said vessel comprising a rotatable disc disposed with one'face substantially parallel to said bottom member and provided over said face with a plurality of spaced relatively narrow scraping elements the free ends of which are equally spaced from said bottom member, means for rotating said disc, and second doctoring means for continuously limiting the thickness of the compacted layer on the side wall of said vessel comprising an elongated member extending within said vessel for a distance substantially equal to the height of said side wall and parallel thereto, said elongated member being coplanar with the axis. of rotation of said'vessel, fixed bearing means exteriorly of said vessel for slidably supporting said elongated member, said elongated member having a plurality of spaced scraping members extending radially in a row therefrom, the free ends of said scraping members being equally spaced from said side wall and presenting relatively narrow scraping edges, and means exteriorly of said vessel for reciprocating said elongated member in said bearings independently of the rotation of said first doctoring means, the stroke of reciprocation of said elongated member being at least equal to the space between adjacent scraping members.

References Cited in the file of this patent UNITED STATES PATENTS 

